A heat gun or hair dryer can help smooth out the wrinkles when you're done. Take your time, be careful not to staple too close to the tank, or any edges.I replaced both my 02 cover and my nephews 96 440 cover, I bought a $15 air stapler at menards (I'm sure somethin similar near you) and used 5/8 length staples, that worked perfectly. I kept my old cover and used pieces of it to reinforce stress points that tear first like the top edge of the plastic pan between the foam and gas tank and the back corners below the tail light.
I layed a strip of carpet out on my chest freezer in my garage and used that as my bench since you'll be doing a lot of the work with it upside down. Just make sure you get your seams as even as possible and DO NOT pull the material too tight. That will either cause the cover to be off center or some staples could pull through causing the cover to have rips in it.
Good luck and post some pics when ur done.